The City watchdog has imposed a fine of almost £13.3 million ($20m) on Bank of America's Merrill Lynch International (MLI) for incorrectly reporting millions of financial transactions.
The Financial Conduct Authority (FCA) confirmed the penalty, first reported by Sky News last night, saying it related to more than 35 million transactions.
The fine, the highest imposed by the regulator on such an issue, also took into account a further 121,400 transactions it failed to report, the FCA said.
It added that the size of the fine reflected the bank's "poor history" in relation to such reporting and followed a previous penalty handed to the group in 2006.
Georgina Philippou, the FCA's acting director of enforcement and market oversight, said: "Proper transaction reporting really matters.
"Merrill Lynch International has failed to get this right again – despite a Private Warning, a previous fine, and extensive FCA guidance and enforcement action in this area.
"The size of the fine sends a clear message that we expect to be heard and understood across the industry.
"Accurate and timely reporting of transactions is crucial for us to perform effective surveillance for insider trading and market manipulation in support of our objective to ensure that markets work well and with integrity."
MLI agreed to settle at an early stage of the investigation, and received a 30% reduction in their overall fine.
It is the latest in a string of fines handed out by the FCA to major financial institutions for incorrectly reporting transactions.
Last August, Deutsche Bank was ordered to pay £4.7m over similar offences, while Royal Bank of Scotland (RBS) was hit with a £5.6m fine in 2013.
Barclays, Commerzbank and Societe Generale are among the other major lenders to have fallen foul of FCA rules on transaction reporting, with the regulator engaging in a determined clampdown on poor practice in the area.
